Missouri is home to more than 300 species of spiders, and while the vast majority are harmless, two — the brown recluse and the black widow — are medically significant and found throughout the St. Louis area. Whether your concern is venomous species or simply the creep factor of finding spiders in your bathroom at 2 a.m., the good news is that most spider problems can be prevented with a combination of habitat management, exclusion, and targeted treatment.

In this guide, we cover the most common Missouri spiders, practical prevention tips you can do yourself, and when it makes sense to call a professional for backup.

Common Spiders in Missouri Homes

Brown Recluse

The brown recluse (Loxosceles reclusa) is Missouri’s most concerning house spider. It is light to medium brown with a distinctive violin-shaped marking on its back and six eyes arranged in three pairs (most spiders have eight). Brown recluses prefer dark, undisturbed areas — closets, attics, basements, behind furniture, inside cardboard boxes, and in seldom-worn shoes. They are not aggressive, but they will bite if accidentally pressed against skin, and their venom can cause tissue necrosis that requires medical attention.

Brown recluse infestations in Missouri can be severe. It is not uncommon for professional inspections to find dozens or even hundreds in a single home. They thrive in the climate of the St. Louis metro and are the number one spider-related service call we receive at Roberts Pest Control.

Black Widow

The southern black widow (Latrodectus mactrans) is found throughout Missouri, though it is more common outdoors than inside. Females are shiny black with the iconic red hourglass marking on the underside of their round abdomen. Black widows favor dark, sheltered spaces — woodpiles, garages, sheds, meter boxes, and outdoor furniture. Their bite is painful and can cause systemic symptoms including muscle cramps, nausea, and difficulty breathing, especially in children and the elderly.

Wolf Spiders

Wolf spiders are large, hairy, fast-moving spiders that hunt prey on the ground rather than building webs. They are common across Missouri and frequently enter homes in fall seeking warmth. While they look intimidating and can grow larger than a quarter, wolf spiders are not dangerous to humans. They are solitary hunters, so finding one does not indicate an infestation. However, their size and speed make them one of the most startling spiders to encounter indoors.

Common House Spider & Cellar Spider

The common house spider and the cellar spider (often called “daddy longlegs”) are the cobweb builders you see in corners, basements, and garages. They are completely harmless and actually beneficial — they catch flies, mosquitoes, and other nuisance insects. However, heavy web accumulation is unsightly, and a large population may indicate an underlying pest issue that is providing them with food. Visit our Pest Library for photos and identification help.

Prevention Tips: How to Keep Spiders Out

1. Seal Cracks, Gaps, and Entry Points

Spiders enter your home through the same gaps that let in every other pest. Inspect your home’s exterior for cracks in the foundation, gaps around windows and doors, openings where utility lines enter, and damaged weather stripping. Use silicone caulk for small cracks and expanding foam for larger gaps. Pay attention to weep holes in brick — install weep hole covers that allow airflow but block pests. Door sweeps on exterior doors are one of the most effective and inexpensive exclusion measures you can install.

2. Reduce Clutter Inside and Out

Spiders — especially brown recluses — love clutter. Cardboard boxes, piles of clothing, stacked newspapers, and crowded storage areas provide the dark, undisturbed hiding spots they need. Replace cardboard boxes with sealed plastic containers, keep storage areas organized, and avoid leaving clothing or shoes on the floor. Outside, move woodpiles, leaf debris, and landscape timbers away from the foundation. The less shelter you provide, the fewer spiders you will harbor.

3. Manage Outdoor Lighting

Standard white outdoor lights attract flying insects, which in turn attract the spiders that eat them. Switch to yellow or sodium vapor bulbs for exterior lights, or use warm-toned LED bulbs that attract fewer insects. Position lights away from doorways when possible — illuminate the area you need, but direct the light source away from entry points to keep the insect buffet away from your doors.

4. Remove Webs Regularly

Regularly knocking down webs with a broom or duster discourages spiders from re-establishing in the same spot. Focus on corners, eaves, window frames, porch ceilings, and garage door frames. Consistent web removal is more effective than a one-time cleanout because it disrupts the spider’s ability to catch food in that location, eventually driving it elsewhere.

5. Control the Food Source

Spiders go where the food is. If you have a lot of spiders, you almost certainly have a lot of insects — ants, flies, gnats, moths, or other prey species. Addressing the underlying insect problem through general pest control is one of the most effective ways to reduce spider populations. When you cut off their food supply, spiders have no reason to stay.

6. Use Sticky Traps for Monitoring

Placing sticky traps (also called glue boards) along baseboards, in closets, behind furniture, and in garage corners helps you monitor spider activity and catch spiders before they establish a presence. Sticky traps are especially useful for detecting brown recluse activity — a few recluses on a trap in a short period indicates a population that warrants professional treatment.

When DIY Is Not Enough

Prevention measures work well for keeping casual spider visitors out, but they have limits. If you are dealing with a brown recluse infestation, a persistent spider problem despite your best efforts, or a situation where venomous spiders pose a risk to your family, professional treatment is the right call.

Professional spider control includes targeted residual treatments in cracks, crevices, and harborage areas where spiders hide — areas that over-the-counter sprays simply cannot reach effectively. At Roberts Pest Control, we use products and application methods specifically chosen for Missouri’s most common spider species, with a focus on long-lasting control rather than temporary knockdown.

For brown recluse infestations, we typically recommend a comprehensive treatment program that includes interior crack-and-crevice treatment, exterior perimeter application, de-webbing, and ongoing monitoring with sticky traps. Severe infestations may require multiple visits to achieve full control, as recluses live in deep harborages that take time to reach.